(a) Field of the Invention
The present invention relates to a device and method for driving a plasma display panel (PDP). More specifically, the present invention relates to a PDP sustain-discharge circuit or an address driving circuit.
(b) Description of the Related Art
In general, a PDP is a flat plate display for displaying characters or images using plasma generated by gas discharge. Pixels ranging from hundreds of thousands to more than millions are arranged in a matrix form according to the size of the PDP. PDPs are categorized as direct current (DC) PDPs and alternating current (AC) PDPs according to patterns of the waveforms of applied driving voltages and structures of discharge cells.
Current directly flows in discharge spaces while a voltage is supplied to the DC PDP, because electrodes of the DC PDP are exposed to the discharge spaces. Therefore, a resistor for restricting the current must be provided to the DC PDP. On the other hand, in the case of the AC PDP, the current is restricted due to the natural formation of a capacitance component because a dielectric layer covers the electrodes. The AC PDP has a longer life than the DC PDP, since the electrodes are protected against shock caused by ions during discharge.
In general, a method for driving the AC PDP includes a reset period, an addressing period, a sustain period, and an erase period.
In the reset period, the states of the respective cells are reset in order to smoothly address the cells. In the addressing period, the cells that are turned on and the cells that are not turned on in a panel are selected, and wall charges are accumulated to the cells that are turned on (i.e., the addressed cells). In the sustain period, discharge is performed in order to actually display pictures on the addressed cells. In the erase period, the wall charges of the cells are reduced to thereby terminate sustain-discharge.
In the AC PDP, since a panel between an address electrode, a sustain electrode, and a scan electrode operates as a capacitive load, it is generally referred to as a panel capacitor. Reactive power is required in order to apply waveforms for the addressing or the sustain-discharge because of capacitance of the panel capacitor. A circuit for recovering and re-using the reactive power is referred to as a power recovery circuit. L. F. Weber discloses the power recovery circuits in the U.S. Pat. Nos. 4,866,349 and 5,081,400.
However, the conventional power recovery circuit only uses resonance between a panel capacitor and an inductor coupled to the panel capacitor, and it normally operates only when a power recovery capacitor is charged with a voltage corresponding to half external power. Since the conventional power recovery circuit has a loss generated from itself, such as a switch's conduction loss and switching loss, during the recovery process it fails to recover the entire energy. Accordingly, since a panel voltage may not be increased or decreased to a desired voltage level, switches problematically perform hard switching to thereby generate power loss, and rising time and falling time of the panel voltage becomes longer.